1. Field of the Invention
This invention relates generally to a master template for contact magnetic transfer of magnetic patterns and to a method for making the template.
2. Description of the Related Art
Contact magnetic duplication or transfer (CMT), sometimes referred to as magnetic printing, is a method of instantaneous recording of magnetic patterns onto magnetic media. In a magnetic recording hard disk drive, each disk contains a fixed, pre-recorded servo pattern of magnetized servo regions or blocks that are used to position the recording head to the desired data track. In the CMT method for forming the servo pattern a “master” disk or template is used that contains regions or islands of soft (low-coercivity) magnetic material in a pattern corresponding to the servo pattern that is to be transferred to the magnetic recording disk (the “slave” disk).
The CMT master template is typically a rigid substrate or a rigid substrate with a plastic film formed on it. These types of master templates have been described in U.S. Pat. Nos. 6,347,016 B1 and 6,433,944 B1; Japanese published application JP2002-342921; and by Ishida, T. et al., “Magnetic Printing Technology-Application to HDD”, IEEE Transactions on Magnetics, Vol 39, No. 2, March 2003, pp 628–632.
In U.S. Pat. No. 6,798,590 B2, assigned to the same assignee as this application, a CMT method is described that uses a flexible master template and a differential gas pressure to press the pattern of magnetic islands against the slave disk. The pattern of magnetic islands is formed on the template by electroplating or evaporation of the magnetic material through a resist pattern, followed by liftoff of the resist. However, this process can result in variations in the surfaces of the magnetic islands and irregularities in the shape of the magnetic islands.
What is needed is an improved CMT master template and method for making it.